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b472113 2 points ago +2 / -0

No problems with the camshaft or the valves. I've haven't heard that.

The only thing I can think of is that the lifters are mechanical and they need to be adjusted every 15,000 miles. If not, then the engine begins to run rougher and rougher.

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Dirty30 1 point ago +1 / -0

It sounds like your camshaft should be good. You can inspect it by removing the engine oil filler cap on the valve cover( Note: Engine NOT Running!)

Again, with engine NOT running, look down with torch at cam lobes for signs of excessive wear and you can feel with your finger. Minor wear is really nothing to be concerned about.

From the late 1970s up into the mid 1990s we were replacing worn camshafts, rocker arms and even the valve springs!

Then in the mid 1990s, a senior technician in Mercedes Benz New South Wales, (Australia) said" fellas, I'm not telling you this, but with the camshafts on the 300 D engines, get the new camshaft and rocker arms treated at an engine reconditioner or machine shop to surface harden them, that will fix the wear problem"

The problem was Benz didn't surface harden the cam lobes and rocker arm contact surfaces properly and as on cold start oil takes around 10-15 seconds to get to the top of the engine, wear would happen.

Don't worry about this,if your camshaft is still good and you have had the vehicle for a while, you camshaft has been treated by the factory or after market.

In Australia, the service interval for tappet adjustment is ever 20,000 km (12,000 miles) The inlet valve clearance is close(0.004 in cold)

Another thing to keep your eye on is the vacuum shut off cell on the end of the injector pump( round anodised, gold coloured can like vacuum cell with rubber hose and plastic vacuum line connected to it)

Remove this rubber hose from the vacuum shut off cell. There should be NO engine oil present in this rubber hose. If there is engine oil present, the vacuum diaphragm is damaged.

If left in this state, engine oil will be draw up the vacuum line to the ignition switch and cause engine oil to leak out under dashboard.

Also keep an eye on the large vacuum hose going from the engine mounted vacuum pump to the brake power booster unit.

The diaphragm in the engine vacuum pump can fail and engine oil can be draw up into the power booster unit.

Also keep an eye on reverse gear. Delayed engagement or shuddering can be caused the band adjuster becoming lose, usually easy to repair.

Those are some of the common problems with the 300 D. With good servicing, there are usually minimal problems. The 300 D is a good vehicle.

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b472113 2 points ago +2 / -0

Thanks for all the information.

I know there were several different diesel engines in cars named 300D from 1977 until the mid 1990's. The 617 was one of them and I believe there were at least two other different diesel engines in cars named 300D.

Over the years I caroused the 616/617 diesel forums on the web so it's always good to get more info, thanks.

Mercedes put special exhaust valves on these 617 turbo diesels. THEY WERE different from the non turbo 617s. I believe they had chromium in them. MBZ really strived for excellence. With that in mind it boggles the mind why they wouldn't do something as simple and necessary as hardening camshaft lobes.

I bought this 300D turbo diesel in the late '80s with 80,000 miles on it. I put 300,000 miles on it since (@ 500,000 km).

The only thing I replaced on it was the engine vacuum pump, and that's only because I managed to procure a new factory pump for free and put it on for the hell of it.

There's a little rust, some lag in the rear axle, a few water leaks (easily fixed with bleach because the drainage lines get gummed up). Other than these few little nagging issues the thing has been solid as a rock.

Thanks again, take care.